1. Field of the Invention
The present disclosure relates to an electrochemical deposition method enabling to obtain CuSCN nanostructures, and especially nanowires, on an electrically-conductive or semiconductor substrate.
Such nanostructures may be used as transparent p-type semiconductor, on an electrically-conductive or semiconductor substrate, in an optoelectronic device such as an organic light-emitting diode (OLED), a polymer light-emitting diode (PLED), a photovoltaic device (PV), or an OPD.
2. Description of Related Art
Organic photovoltaic cells (PV) are devices capable of converting solar energy into electric energy by means of the use of semiconductor materials, to produce a photovoltaic effect. Active materials, as well as the architectures of these devices, are still evolving to meet performance and lifetime criteria enabling to widen the field of application of such technologies.
As a reminder, the conventional and inverse structures of organic PV cells are schematically shown in FIG. 1A and in FIG. 1B, respectively.
In a conventional architecture, a substrate 1 is covered with the following successive layers:                a conductive layer 2 behaving as a first electrode;        a p-type semiconductor layer 3;        an active layer 4;        an n-type semiconductor layer 5; and        a conductive layer 6 behaving as a second electrode.        
In an inverse structure, the stack has the following sequence:                a substrate 1;        a conductive layer 6 behaving as a first electrode;        an n-type semiconductor layer 5;        an active layer 4;        a p-type semiconductor layer 3;        a conductive layer 2 behaving as a second electrode.        
Many p-type semiconductor and transparent metal oxides have been used as P interface layers in OPV cells. The most current are nickel oxide (NiO), molybdenum oxide (MoO5), tungsten oxide (WO3), or vanadium oxide (V2O5). However, few studies bear on the use of CuSCN, while this material has properties similar to those of the previously-mentioned oxides, being capable of being electrochemically deposited.
A method of electrochemical preparation of crystal CuSCN layers on rigid glass/ITO substrates, by cathode reduction of triethanolamine-complex Cu(II), in the presence of thiocyanates anions has been described (Ni et al., 2007). The crystal CuSCN layers thus formed are obtained by homogeneous growth in at least two directions (so-called two-dimensional or 2D structuring).
Selk et al. (2008) have described a method allowing the variation of the morphology of CuSCN layers electrochemically deposited on rigid glass/FTO substrates from an electrolyte in a water/ethanol solvent.
Wu et al. (2005) have described a method of electrochemical preparation (in potentiostatic and galvanostatic mode) of crystal CuSCN layers on rigid glass/ITO substrates. The method is carried out by cathode reduction of disodium EDTA-complexed Cu(II), resulting in a high pH, in the presence of thiocyanate ions. The obtained layers have a non-orderly so-called “2D” structuring.
Wu et al. (2007) have also described a method for electrochemically depositing CuSCN on a porous n-type TiO2 film. In a first step, an electrolytic solution is prepared as described in document Wu et al. of 2005, after which the pH is lowered to 2-2.6 by addition of sulfuric acid (H2SO4).
Further, a method for integrating the previously-described “2D” layers in cells having a structure such as: ITO/CuSCN/P3HT/P3HT:PCBM/Al (Takahashi et al., 2007) has been described.
Finally, Chen et al. (2003) have described a method for manufacturing field-effect transistors from vertical CuSCN nanowires on a flexible substrate, formed through a matrix pierced with cylindrical openings.
An object of the invention tends to develop new architectures based on CuSCN and new methods for obtaining these architectures, capable of being integrated in optoelectronic devices such as OLEDs, PLEDs, PVs, and OPDs and enabling to improve their efficiencies and their stability.